Chemical changes
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
What happens when a metal reacts with oxygen?
• The metal atoms have been oxidised to form a metal oxide. Eg, Calcium + Copper Oxide -> Calcium oxide + copper Calcium has been oxidised (gained oxygen) Copper has been reduced (lost oxygen) REDUCTION = LOSS OF OXYGEN OXIDATION = GAIN OF OXYGEN or OXIDATION = LOSS OF ELECTRONS REDUCTION = GAIN OF ELECTRONS
Metal + Water ->
Metal Hydroxide (alkali) + Hydrogen
How can we determine the order of reactivity of metals?
React them with water and observe how vigorously they react.
State the reactivity series:
Potassium Sodium Lithium Calcium Magnesium – Carbon (non-metal) Zinc Iron – Hydrogen (non-metal) Copper Please Stop Letting Cows Make Zebras In Cages.
Describe the reactivity of Potassium, Sodium and Lithium with water at room temperature.
They react rapidly with water at room temperature.
Describe the reactivity of calcium with water at room temperature.
Reacts quite rapidly with water at room temperature.
Describe the reactivity of magnesium, zinc, iron and copper with water at room temperature.
No reaction. • If we want to work out their reactivity, react them with dilute acids if we want to compare their reactivity.
Describe the reactivity of Potassium, Sodium and Lithium with dilute acid.
Dangerously fast and vigorous reaction. • We should never do this because it is too dangerous because they react too vigorously.
Describe the reactivity of calcium with dilute acid.
Extremely vigorous reaction.
Describe the reactivity of magnesium with dilute acid.
Rapid reaction.
Describe the reactivity of zinc with dilute acid.
Quite rapid reaction.
Describe the reactivity of iron with dilute acid.
Quite slow reaction.
Describe the reactivity of copper with dilute acid.
No reaction.
What does the reactivity of a metal depend on?
Its ability to lose electrons on the outermost shell and form a positive ion.
State why we can find pure gold in the Earth.
Because it is so unreactive, so will not react with other metals in the Earth.
True or false, a more reactive metal/element will displace/push out a less reactive element from its compound?
True.
How can we extract metals from their ores?
Metals less reactive than carbon can be extracted through displacement reactions - using carbon to displace the metal from the metal oxide compound. We use carbon because other metals are too expensive. The metal is reduced The carbon is oxidised
Explain oxidation and reduction in terms of loss and gain of electrons
REDUCTION = LOSS OF OXYGEN OXIDATION = GAIN OF OXYGEN or OXIDATION = LOSS OF ELECTRONS REDUCTION = GAIN OF ELECTRONS eg S + 2e^- -> S2- in this case, sulfur has been reduced, because it has gained electrons eg Mg -> Mg2+ e^- In this case, magnesium has been oxidised because it has LOST electrons. OIL RIG ^above reactions are called half equations. - should also be able to identify oxidation and reduction reactions in symbol equations.
What state symbol are acids followed by?
aq (aqueous) because they are dissolved in water.
Ionic equations and displacement reactions practice questions
Chemical formula for Hydrochloric acid Sulfuric acid Nitric acid
HCl (aq) H2SO4 (aq) HNO3 (aq)
Acids react with metals to produce?
Salt and hydrogen.
In aqueous solutions, what ions do acids release?
a H+ ion. eg They ionise and release a H+ ion. HCL -> H+ + Cl-
What are alkalis and bases?
A base is a chemical which can neutralise acids to produce salt and water. eg Iron(iii)hydroxide An alkali is an soluble base. eg Sodium hydroxide Bases are usually metal hydroxides and metal oxides.